lineedit: fix multi-line PS1 handling: calculate PS1 length from last \n

function                                             old     new   delta
parse_and_put_prompt                                 755     774     +19

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 30 insertions, 14 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index ecf3066b1..b3f16cd9d 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -38,6 +38,14 @@
  * and the \] escape to signal the end of such a sequence. Example:
  *
  * PS1='\[\033[01;32m\]\u@\h\[\033[01;34m\] \w \$\[\033[00m\] '
+ *
+ * Unicode in PS1 is not fully supported: prompt length calulation is wrong,
+ * resulting in line wrap problems with long (multi-line) input.
+ *
+ * Multi-line PS1 (e.g. PS1="\n[\w]\n$ ") has problems with history
+ * browsing: up/down arrows result in scrolling.
+ * It stems from simplistic "cmdedit_y = cmdedit_prmt_len / cmdedit_termw"
+ * calculation of how many lines the prompt takes.
  */
 #include "libbb.h"
 #include "unicode.h"
@@ -1759,34 +1767,36 @@ static void ask_terminal(void)
 #define ask_terminal() ((void)0)
 #endif
 
+/* Called just once at read_line_input() init time */
 #if !ENABLE_FEATURE_EDITING_FANCY_PROMPT
 static void parse_and_put_prompt(const char *prmt_ptr)
 {
+        const char *p;
         cmdedit_prompt = prmt_ptr;
-        cmdedit_prmt_len = unicode_strlen(prmt_ptr);
+        p = strrchr(prmt_ptr, '\n');
+        cmdedit_prmt_len = unicode_strlen(p ? p+1 : prmt_ptr);
         put_prompt();
 }
 #else
 static void parse_and_put_prompt(const char *prmt_ptr)
 {
-        int prmt_len = 0;
-        size_t cur_prmt_len = 0;
-        char flg_not_length = '[';
+        int prmt_size = 0;
         char *prmt_mem_ptr = xzalloc(1);
 # if ENABLE_USERNAME_OR_HOMEDIR
         char *cwd_buf = NULL;
 # endif
-        char timebuf[sizeof("HH:MM:SS")];
+        char flg_not_length = '[';
         char cbuf[2];
-        char c;
-        char *pbuf;
 
         /*cmdedit_prmt_len = 0; - already is */
 
         cbuf[1] = '\0'; /* never changes */
 
         while (*prmt_ptr) {
+                char timebuf[sizeof("HH:MM:SS")];
                 char *free_me = NULL;
+                char *pbuf;
+                char c;
 
                 pbuf = cbuf;
                 c = *prmt_ptr++;
@@ -1924,16 +1934,22 @@ static void parse_and_put_prompt(const char *prmt_ptr)
                         } /* if */
                 } /* if */
                 cbuf[0] = c;
-                cur_prmt_len = strlen(pbuf);
-                prmt_len += cur_prmt_len;
-                if (flg_not_length != ']') {
-#if 0 /*ENABLE_UNICODE_SUPPORT - won't work, pbuf is one BYTE string here. FIXME */
-                        cmdedit_prmt_len += unicode_strlen(pbuf);
+                {
+                        int n = strlen(pbuf);
+                        prmt_size += n;
+                        if (c == '\n')
+                                cmdedit_prmt_len = 0;
+                        else if (flg_not_length != ']') {
+#if 0 /*ENABLE_UNICODE_SUPPORT*/
+/* Won't work, pbuf is one BYTE string here instead of an one Unicode char string. */
+/* FIXME */
+                                cmdedit_prmt_len += unicode_strlen(pbuf);
 #else
-                        cmdedit_prmt_len += cur_prmt_len;
+                                cmdedit_prmt_len += n;
 #endif
+                        }
                 }
-                prmt_mem_ptr = strcat(xrealloc(prmt_mem_ptr, prmt_len+1), pbuf);
+                prmt_mem_ptr = strcat(xrealloc(prmt_mem_ptr, prmt_size+1), pbuf);
                 free(free_me);
         } /* while */